Major or Mild Frontotemporal Neurocognitive Disorder
DSM-IV In DSM-IV, this disorder is called Dementia Due to Pick's Disease For more information, see Dementia Due to Other General Medical Conditions The essential feature of Dementia Due to Pick's Disease is the presence of a dementia that is judged to be the direct pathophysiological consequence of Pick's disease. Pick's disease is a degenerative disease of the brain that particularly affects the frontal and temporal lobes. As in other frontal lobe dementias, Pick's disease is characterized clinically by changes in personality early in the course, deterioration of social skills, emotional blunting, behavioral disinhibition, and prominent language abnormalities. Difficulties with memory, apraxia, and other features of dementia usually follow later in the course. Prominent primitive reflexes (snout, suck, grasp) may be present. As the dementia progresses, it may be accompanied by either apathy or extreme agitation. Individuals may develop such severe problems in language, attention, or behavior that it may be difficult to assess their degree of cognitive impairment. Structural brain imaging typically reveals prominent frontal and/or temporal atrophy, and functional brain imaging may localize frontotemporal hypometabolism, even in the absence of clear structural atrophy. The disorder most commonly manifests itself in individuals between ages 50 and 60 years, although it can occur among older individuals. Pick's disease is one of the pathologically distinct etiologies among the heterogenous group of dementing processes that are associated with frontotemporal brain atrophy. The specific diagnosis of a frontal lobe dementia such as Pick's disease is usually established at autopsy with the pathological finding of characteristic intraneuronal argentophilic Pick inclusion bodies. Clinically, Pick's disease often cannot be distinguished with certainty from atypical cases of Alzheimer's disease or from other dementias that affect the frontal lobes. DSM-5 For more information, see Major and Mild Neurocognitive Disorders Diagnostic Criteria A'''. The criteria are met for a major or mild neurocognitive disorder. '''B. The disturbance has insidious onset and gradual progression. C'''. Either (1) or (2): # Behavioral variant: #* '''a. Three or more of the following behavioral symptoms: #** i'''. Behavioral disinhibition. #** '''ii. Apathy or inertia. #** iii. Loss of sympathy or empathy. #** iv. Perseverative, stereotyped or compulsive/ritualistic behavior. #** v'''. Hyperorality and dietary changes. #* '''b. Prominent decline in social cognition and/or executive abilities. # Language variant: #* a'''. Prominent decline in language ability, in the form of speech production, word finding, object naming, grammar, or word comprehension. '''D. Relative sparing of learning and memory and perceptual-motor function. E'''. The disturbance is not better explained by cerebrovascular disease, another neurodegenerative disease, the effects of a substance, or another mental, neurological, or systemic disorder. '''Probable frontotemporal neurocognitive disorder is diagnosed if either of the following is present; otherwise, possible frontotemporal neurocognitive disorder should be diagnosed: # Evidence of a causative frontotemporal neurocognitive disorder genetic mutation, from either family history or genetic testing. # Evidence of disproportionate frontal and/or temporal lobe involvement from neuroimaging. Possible frontotemporal neurocognitive disorder is diagnosed if there is no evidence of a genetic mutation, and neuroimaging has not been performed. Differential Diagnosis Other neurocognitive disorders Other neurodegenerative diseases may be distinguished from major or mild frontotemporal NCD by their characteristic features. In major or mild NCD due to Alzheimer's disease, decline in learning and memory is an early feature. However, 10%-30% of patients presenting with a syndrome suggestive of major or mild frontotemporal NCD are found at autopsy to have Alzheimer's disease pathology. This occurs more frequently in individuals who present with progressive dysexecutive syndromes in the absence of behavioral changes or movement disorder or in those with the logopenic variant. In major or mild NCD with Lewy bodies, core and suggestive features of Lewy bodies must be present. In major or mild NCD due to Parkinson's disease, spontaneous parkinsonism emerges well before the cognitive decline. In major or mild vascular NCD, depending on affected brain regions, there may also be loss of executive ability and behavioral changes such as apathy, and this disorder should be considered in the differential diagnosis. However, history of a cerebrovascular event is temporally related to the onset of cognitive impairment in major or mild vascular NCD, and neuroimaging reveals infarctions or white matter lesions sufficient to account for the clinical picture. Other neurological conditions Major or mild frontotemporal NCD overlaps with progressive supranuclear palsy, corticobasal degeneration, and motor neuron disease clinically as well as pathologically. Progressive supranuclear palsy is characterized by supranuclear gaze palsies and axial-predominant parkinsonism. Pseydobulbar signs may be present, and retropulsion is often prominent. Neurocognitive assessment shows psychomotor slowing, poor working memory, and executive dysfunction. Corticobasal degeneration presents with asymmetric rigidity, limb apraxia, postural instability, myoclonus, alien limb phenomenon, and cortical sensory loss. Many individuals with behavioral-variant major or mild frontotemporal NCD show features of motor neuron disease, which tend to be mixed upper and predominantly lower motor neuron disease. Other mental disorders and medical conditions Behavioral-variant major or mild frontotemporal NCD may be mistaken for a primary mental disorder, such as major depression, bipolar disorders, or schizophrenia, and individuals with this variant often present initially to psychiatry. Over time, the development of progressive neurocognitive difficulties will help to make the distinction. A careful medical evaluation will help to exclude treatable causes of NCDs, such as metabolic disturbances, nutritional deficiencies, and infections.